幾題考古題 - 經濟

1.If the cross-price elasticity of the demand for type- writers

with respect to the price of computers is 0.25, the own price

elasticity of demand for typewriters is -0.5, and the price

elasticity of the supply of typewriters is 1.0, how much would

the price and quantity of typewriters exchanged change if

computers became 20 percent cheaper?

答案: 價格跟數量都下跌1/30

這要怎麼算，而且價格下跌數量也跟著下跌??


2.假設在 two- market system 中 Ex 和 Ey 分別為物品 X 和 Y 的超

額需求，Ex = 100 -5Px +Py， Ey = 50 +2Px -2Py, 則

a.X 和 Y 二者是 gross substitutes

b.X 和 Y二者是 gross complements

c.X 和 Y 二者彼此是 independent.

d X 和 Y 即為 gross substitutes,亦是 gross complements.


這題答案給: a, b , c 都對，

我的想法; a 跟 b 都對了，那為什麼d就不行呢??



3. Suppose Charlie Parker CDs cost $10 a piece and Lester Young

CDs cost $5 a piece. You have $40 to spend on CDs. The marginial

utility that you derive from additional CDs is as follows:

Units Consumption Charlie Parker Lester Young

1 60 30
2 40 28
3 30 24
4 20 20
5 10 10

How many of each CD would you buy to maximize your utility?

答案: Parker 2張, Young4張

我的答案是 Parker 3張，Young 2張．明明Young的邊際效用沒有比

Parker來得大啊??，在所得允許之下不是要先選擇邊際效用

較大的嗎??







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